In general, metallic wire, such as copper wire, is produced from rod stock by passing, i.e. pulling or drawing, the rod through a series of reducing dies, wherein each die produces an output rod or wire of lesser diameter than the input until the output of the final stage is wire of the desired diameter. In order that the drawing process be facilitated, the material being drawn, and also the dies, are heavily lubricated with a suitable lubricant to reduce friction. With proper lubrication the amount of pulling power needed and the concomitant incidence of wire breakage are reduced, and, generally, the overall quality of the wire is improved. As a consequence, much attention has been directed to apparatus and methods of achieving proper lubrication. In U.S. Pat. No. 3,526,115 of Armstrong et al, for example, there is shown a wire drawing arrangement and a method for lubricating the wire and dies to produce good quality wire, in which the wire is passed through a lubricant filled tubular chamber before entering the die. According to the disclosure of that patent, it was found that lubricant under high pressure within the chamber was more effective than lubricant under low or zero pressure.
Most metallic materials, most particularly copper, tend to oxidize fairly rapidly under the heat and humidity conditions generally encountered in the pre-drawing stages and the drawing process itself. Thus the surface of copper rod develops a thin layer or film of copper oxide even before being introduced into a die drawing apparatus.